How much should arrow warning boards be dimmed for nighttime operation?

Dimming arrow warning boards for nighttime operation is crucial for several reasons, including minimizing glare for drivers and reducing light pollution in the environment. Dimming the boards by 50% strikes an effective balance between maintaining visibility for safety while ensuring they are not excessively bright and distracting during nighttime conditions.

This level of dimming allows the board to remain highly visible to approaching drivers without overwhelming their vision, which is particularly important in low-light situations. It also helps prevent the temptation for distracted driving, which could lead to accidents in nighttime settings.

Other options might either lead to insufficient visibility, especially in areas where there are low levels of ambient lighting, or result in overly bright displays that could create hazardous driving conditions. Therefore, a 50% reduction is established as a standard that meets both safety and operational needs effectively.